This dissertation explores the central place of semiotic interpretation in the instruction of several medieval genres--Latin and vernacular religious drama, French fabliaux, and Spanish exempla--encompassing both the lesson that is taught and the method for teaching it. It is my contention that teaching the proper way to interpret signs is the didactic focus in these genres and that their authors were also deeply concerned with scrutinizing their own use of signs in conveying this instruction. As medieval sign theory finds its origin in Augustinian semiotics, Chapter 1 of my dissertation raises key considerations in Augustine's discussions of signa that would continue to inform later treatments of interpretation. I establish the intrinsic connection between teaching and the interpretation of signs in his writings as well as his frequent ambivalence on the subject. For the Bishop of Hippo, the proper understanding of sacred signs is the paramount lesson of Christian instruction, with misreading Jews as the primary emblem of faulty interpretation. Signs are also a concern for the pedagogical process (doctrina in its second sense) because the success of any lesson is dependent on the effectiveness of its signs to communicate. Yet, Augustine also places the burden of understanding squarely on the learner who must labor with interpretation and attain personal enlightenment. Augustine clearly admires the pagan classics and acknowledges the dominant role of words in instruction, but, for him, the falsified verbal signs of fiction have no value for teaching. Moreover, non-verbal communication--through inner inspiration and visually apprehended signs or res significandi--is vastly superior to fallen language in transmitting meaning as well as creating memory of what is learned. Yet, Augustine also evinces a suspicion of sensory data. These ideas, including doubts about vision and the value of learning through fictive works, would continue to inform the instruction present in later medieval texts. Chapter 2 examines the persistence of Augustinian concepts in medieval religious plays from early church drama through the Middle English cycles. These texts are mainly concerned with teaching the proper interpretation of sacred signa, following Augustine, particularly through the characterization of Jews who fail to read signs correctly. Medieval religious drama also endorses the value of non-verbal communication--through a reliance on individual faith as a precursor to comprehension and through dramatic res such as setting, gesture, and costume--both in conveying semiotic instruction and rendering it memorable. Jewish characters are further portrayed as working against these ideas, representatives of a failure to learn by seeing and believing, who seek instead to force interpretation through violence. Chapter 3 examines a genre in which the presence of doctrinal instruction is debatable, the French fabliaux, and identifies a consistent emphasis on the risks of interpretation across the vast corpus. All signs, verbal and visual, are potentially insufficient in constructing meaning and open to manipulation, emblematized primarily by the actions of deceptive women. Fabliaux evince a self-consciousness about their ability to present these hazards both because they do so through the medium of poetry and because they must rely on signs to make their point. However, the genre ultimately flaunts the insufficiency of its own signs as part of its message, using laughter and mnemonic imagery to promote understanding. Chapter 4 extends the findings on fabliaux to the Spanish Sendebar or Libro de los engaÃ±os, a text of questionable didacticism that also emphasizes the role of women in manipulating signs. The practical wisdom derived from the collection--its interest in good counsel and prudence--can likewise be simplified to the need for careful interpretation of signs in a post-lapsarian world. However, through the didactic insufficiency of its tale-telling enterprise, it ultimately affirms the limits of teaching using signs. My dissertation concludes by examining the persistence of many of these ideas in twenty-first-century pedagogy. Recent emphasis on equipping contemporary students with the tools for interpreting signs in an increasingly image-based culture and on promoting the expanded use of visuals in the classroom reiterate longstanding concerns of doctrina. Assessing the instructional role of signs first raised by Augustine and its reconsideration in medieval texts thus sheds new light on didactic content and purpose that continue to inform our endeavors as teachers today.